Resin composition for sandblasting and surface treatment method

Abstract

The present invention provides a sandblasting resin composition that can form a sandblasting resist layer with good blast resistance that can be removed without the use of alkaline solvents, and a surface processing method using the same. [Solution] A sandblasting resin composition containing a compound having a carboxyl group and an amide group in its molecule, and at least one selected from phenoxy resin and urethane (meth)acrylate.

Description

Technical Field

[0001] The present invention relates to a resin composition for sandblasting and a surface treatment method.

Background Art

[0002] As one of the methods for applying decorations such as characters and patterns to the surface of a base material such as glass, stone, or metal, there is sandblast treatment. Sandblast treatment is a process of spraying an abrasive such as sand onto a base material to cut the surface of the base material. Generally, before sandblast treatment, a sandblast resist layer formed from a resin composition for sandblasting is provided on the base material as a mask material, and after sandblast treatment, the sandblast resist layer is often removed by immersing it in an alkaline solution or the like.

[0003] Various resin compositions for sandblasting have been studied. For example, those containing asphalt and a thermoplastic elastomer have been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, for the purpose of weight reduction, aluminum is sometimes used on the outside of electronic devices such as smartphones. In addition, it is desired to perform sandblast treatment on the surface of such aluminum. However, when amphoteric metals such as aluminum are immersed in an alkaline solution to remove the sandblasting resist layer after sandblasting, the surface may be corroded by the alkali. Therefore, methods for removing the sandblasting resist layer without using alkaline solutions (e.g., removal with organic solvents, removal with tape) are being investigated. Sandblasting resist layers formed from sandblasting resin compositions with compositions that can be removed without using previously proposed alkaline solutions are abrasives that remove the layer during sandblasting, resulting in poor blast resistance.

[0006] The present invention has been made in accordance with these circumstances, and its objective is to provide a sandblasting resin composition that can form a sandblasting resist layer that has good blast resistance and can be removed without using alkaline solvents, and a surface processing method using the same. [Means for solving the problem]

[0007] In other words, the sandblasting resin composition according to the present invention is The present invention is characterized by containing a compound having a carboxyl group and an amide group in its molecule, and at least one selected from phenoxy resin and urethane (meth)acrylate.

[0008] Furthermore, in embodiments of the present invention, it is preferable that the content of compounds having carboxyl groups and amide groups in the molecule is 1.5% to 5.0% by mass.

[0009] Furthermore, in embodiments of the present invention, it is preferable to further contain a silane coupling agent.

[0010] Furthermore, another aspect of the present invention relates to a surface processing method characterized by forming a sandblasting resist layer on a workpiece using the above-described sandblasting resin composition, performing sandblasting, and removing the sandblasting resist layer after sandblasting. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a sandblasting resin composition that can form a resin layer with good blast resistance and that can be removed without using alkaline solvents, and a surface processing method using the same. [Modes for carrying out the invention]

[0012] The following describes the resin composition for sandblasting and the surface treatment method according to this embodiment.

[0013] (Sandblasting resin composition) The sandblasting resin composition according to this embodiment contains a compound having a carboxyl group and an amide group in its molecule, and at least one selected from phenoxy resin and urethane (meth)acrylate, preferably containing a silane coupling agent, and further optionally containing other components.

[0014] <Compounds containing carboxyl groups and amide groups within the molecule> Compounds having carboxyl groups and amide groups in their molecules are included to enable the removal of the sandblasting resist layer formed from the sandblasting resin composition using tape or organic solvents.

[0015] Compounds containing carboxyl and amide groups in their molecules are used as mold release agents. Generally, mold release agents include not only compounds with carboxyl and amide groups in their molecules, but also silicone compounds. However, silicone compounds are incompatible with resin components and therefore do not completely mix with the resin in the resin composition. In other words, silicone compounds exist in an unstable state in the resin composition. When a resin composition containing a silicone compound, applied to a substrate to be processed, is dried, the solvent in the resin composition evaporates, forming a cured product in which the resin component layer and the silicone compound layer are separated into two layers. Over time, the silicone compound migrates to the surface of the cured product (i.e., the side opposite the workpiece), forming a silicone layer. When a silicone layer forms on the surface of the cured product, the adhesive strength to the release tape decreases. As a result, the cured product of the sandblasting resin composition containing the silicone compound becomes difficult to remove using the release tape. On the other hand, compounds having carboxyl groups and amide groups in their molecules have high compatibility with resin components and exist in a stable state in the resin composition, making it possible to remove the sandblasting resist layer formed from the sandblasting resin composition with tape or an organic solvent. For this reason, the sandblasting resin composition according to this embodiment contains compounds having carboxyl groups and amide groups in their molecules.

[0016] Compounds having a carboxyl group and an amide group in the molecule preferably contain a fatty acid amide, more preferably a tertiary fatty acid amide, and even more preferably a tertiary dimethyl fatty acid amide. Examples of such fatty acid amides include saturated fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, N,N-dimethyllauric acid amide, N,N-dimethylmyristic acid amide, N,N-dimethylpalmitic acid amide, N,N-dimethylstearic acid amide, N,N-diethyllauric acid amide, N,N-diethylmyristic acid amide, N,N-diethylpalmitic acid amide, and N,N-diethylstearic acid amide; and unsaturated fatty acid amides such as palmitoleic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, N-oleylpalmitic acid amide, oleic acid N-methylamide, N-stearylerucic acid amide, N,N-dimethyloleic acid amide, and N,N-diethyloleic acid amide. These may be used individually or in combination of two or more.

[0017] The compound having a carboxyl group and an amide group in the molecule may be synthesized as appropriate or a commercially available product may be used. Commercially available products include, for example, MoldWiz INT-120IMC (manufactured by AXEL PLASTICS), Amide AP-1, Diamide Y, Diamide O-200, Diamide I-200 (manufactured by Mitsubishi Chemical Corporation), Neutron, Neutron-2, Neutron-S, Neutron BNT-22H, Neutron PNT- .34, Neutron SNT-F (manufactured by Nippon Seika Co., Ltd., Alflo S-10, Alflo E-10, Alflo P-10 (manufactured by NOF Corporation), Armoslip CP powder, Armoslip HT powder, Armoslip E (manufactured by Lion Specialty Chemicals Co., Ltd.), fatty acid amide S, fatty acid amide O-N, fatty acid amide E (manufactured by Kao Corporation), etc.

[0018] The content of the compound having a carboxyl group and an amide group in the molecule is preferably 1.5% by mass to 5.0% by mass, more preferably 1.5% by mass to 3% by mass, based on the total amount of the resin composition for sandblasting.

[0019] <At least one selected from a phenoxy resin and a urethane (meth)acrylate> The phenoxy resin or urethane (meth)acrylate is contained to improve the blast resistance. The phenoxy resin or urethane (meth)acrylate has a larger molecular weight, flexibility, and good adhesion compared to the epoxy resin contained in a general resin composition not limited to the resin composition for sandblasting, and thus can improve the blast resistance.

[0020] <<Phenoxy resin>> Phenoxy resins include, for example, bifunctional phenols. Bifunctional phenols include, for example, those obtained by polymerizing aromatic diols (such as bisphenol A and bisphenol F) and epichlorohydrin. Such phenoxy resins include, for example, phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenol acetophenone skeleton, novolak skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. These may be used alone or in combination of two or more.

[0021] The phenoxy resin may be synthesized as appropriate or a commercially available product may be used. Commercially available products include, for example, jER1256, jER4250, jER4275 (all of the above are manufactured by Mitsubishi Chemical Corporation), PKH-A, PKH-B, PKH-C, PKH-J, PKH-H, PKF-E, PKCP-80 (all of the above are manufactured by Huntsman Corporation), YP-50, YP-55U, YP-50S, YP-70, FX-293, FX-280S, FX-310 (all of the above are manufactured by Nippon Steel Chemical & Material Co., Ltd.), etc.

[0022] The molecular weight (weight-average molecular weight) of the phenoxy resin is preferably 5,000 to 100,000, more preferably 10,000 to 80,000, even more preferably 20,000 to 50,000, and particularly preferably 30,000 to 45,000. When the molecular weight of phenoxy resin exceeds 100,000, it becomes difficult to remove without using an alkaline solution. This is thought to be because the adhesive force between the workpiece and the sandblasting resist layer becomes too strong. Also, when the molecular weight of phenoxy resin exceeds 100,000, it may become difficult to remove the sandblasting resist layer with an organic solvent. If the sandblasting resist layer becomes difficult to dissolve in an organic solvent, the amount of organic solvent required to dissolve the sandblasting resist layer increases, raising the manufacturing cost of the sandblasting resin composition. On the other hand, if the molecular weight of phenoxy resin is less than 5,000, the blast resistance may deteriorate.

[0023] <<Urethane (meth)acrylate>> Urethane (meth)acrylate is a resin produced, for example, by synthesizing a urethane prepolymer using a polyol and a polyisocyanate, and then adding a (meth)acrylate having hydroxyl groups to it. In this specification, (meth)acrylate is used as a general term encompassing acrylate and methacrylate, and includes either acrylate or methacrylate, or both. The same applies to other similar expressions.

[0024] Urethane (meth)acrylates can be classified according to the number of functional groups they contain in their molecules. Examples include monofunctional urethane (meth)acrylates, difunctional urethane (meth)acrylates, and trifunctional urethane (meth)acrylates. These may be used individually or in combination of two or more types.

[0025] The content of at least one selected from phenoxy resin and urethane (meth)acrylate is preferably 20% to 70% by mass, and more preferably 30% to 65% by mass, relative to the total sandblasting resin composition.

[0026] <Silane coupling agent> Silane coupling agents are included to improve the adhesion between the workpiece and the sandblasting resist layer. Examples of silane coupling agents include silane coupling agents having epoxy groups, silane coupling agents having amino groups, silane coupling agents having mercapto groups, and silane coupling agents having isocyanate groups. These may be used individually or in combination of two or more. When forming a sandblasting resist layer from a sandblasting resin composition using heat drying (heat drying type), a silane coupling agent having an epoxy group is preferred. Furthermore, when forming a sandblasting resist layer from a sandblasting resin composition using UV curing (UV curing type), a silane coupling agent having an acrylic group or a methacrylic group is preferred.

[0027] There are no particular restrictions on the content of the silane coupling agent, and it can be appropriately selected depending on the purpose, but it is preferably 1% to 10% by mass, and more preferably 3% to 7% by mass, relative to the total amount of the sandblasting resin composition.

[0028] <Other ingredients> Other components are not particularly limited as long as they are included in a typical sandblasting resin composition, and can be appropriately selected depending on the purpose. Examples of other components include photopolymerization initiators, photopolymerizable monomers, colorants, thixotropes, and organic solvents.

[0029] <<Photopolymerization initiator>> The photopolymerization initiator is not particularly limited as long as it is one that is commonly used in sandblasting resin compositions, and can be appropriately selected according to the purpose, and any known one can be used. The photopolymerization initiator may be used alone or in combination of two or more types.

[0030] Photopolymerization initiators, for example, bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide Bisacylphosphine oxides such as bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide and bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphine methyl ester, 2-methylbenzoyldiphenylphosphine oxide, and pivaloylphenylphosphine isopropyl Monoacylphosphine oxides such as esters, 2,4,6-trimethylbenzoyldiphenylphosphine oxide; ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 1-hydroxycyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-hydroxy- Hydroxyacetophenones such as 2-methyl-1-phenylpropan-1-one; benzoins such as benzoin, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenones such as benzophenone, p-methylbenzophenone, Michlar's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone;Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, 1,2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone Acetophenones such as N,N-dimethylaminoacetophenone; thioxanthones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, 2 Anthraquinones such as aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoate ethyl ester; 1,2-octanedione, 1-[4-(phenylthio)phenyl]-,2-(O-benzoyl oxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyl Examples include oxime esters such as oxime; titanosenes such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)phenyl)titanium and bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, and tetramethylthiuram disulfide.

[0031] <<Photopolymerizable monomers>> Photopolymerizable monomers are monomers having an ethylenically unsaturated double bond. Examples of such photopolymerizable monomers include conventionally known polyester (meth)acrylates, polyether (meth)acrylates, carbonate (meth)acrylates, epoxy (meth)acrylates, etc. Specifically, alkyl acrylates such as 2-ethylhexyl acrylate and cyclohexyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; mono- or diacrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide, and N,N-dimethylaminopropylacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate; hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, and trishydroxyethyl Examples include polyhydric acrylates derived from polyhydric alcohols such as isocyanurates or their alkylene oxide adducts or ε-caprolactone adducts; polyhydric acrylates derived from phenols such as phenoxyacrylate and bisphenol A diacrylate or their alkylene oxide adducts; acrylates derived from glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and, not limited to the above, acrylates obtained by directly acrylateting polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, and polyester polyols, or by urethane acrylate obtained via diisocyanates, as well as melamine acrylate and methacrylates corresponding to the acrylates. However, urethane (meth)acrylates are excluded as photopolymerizable monomers. These may be used individually or in combination of two or more.

[0032] <<Coloring agent>> The coloring agent is not particularly limited as long as it is one that is commonly used in sandblasting resin compositions, and can be appropriately selected according to the purpose. Conventional and known coloring agents such as black, red, blue, green, yellow, and white can be used, and may be pigments, dyes, or colorants.

[0033] Examples of black colorants include carbon black, zirconium nitride, and Pigment Black 1, 6, 7, 8, 9, 10, 11, 12, 13, 18, 20, 25, 26, 28, 29, 30, 31, and 32. Examples of red colorants include monoazo, disazo, azolake, benzimidazolon, perylene, diketopyrrolopyrrole, condensed azo, anthraquinone, and quinacridone. Blue colorants include phthalocyanine-based and anthraquinone-based compounds, while pigment-based compounds classified as pigments can be used. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Green coloring agents include phthalocyanine-based, anthraquinone-based, and perylene-based compounds. In addition to these, metal-substituted or unsubstituted phthalocyanine compounds can also be used. Examples of yellow colorants include monoazo, disazo, condensed azo, benzimidazolone, isoindolinone, and anthraquinone. Examples of white colorants include rutile or anatase titanium dioxide. In addition, colorants such as purple, orange, and brown may be added to adjust the color tone.

[0034] <<Pixotrope>> The thixotrope is not particularly limited as long as it is used in ordinary sandblasting resin compositions and can be appropriately selected according to the purpose. Examples include fatty acid amides (amide wax type) synthesized from vegetable oil fatty acids and amines; surfactants such as fatty acid esters, polyethers, sulfated oils, and higher alcohol sulfates; polycarboxylic acid esters; polycarboxylic acid amides; and urea-modified compounds.

[0035] <<Organic Solvents>> The organic solvent is not particularly limited as long as it is one that is commonly used in sandblasting resin compositions, and can be appropriately selected depending on the purpose. Examples include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum-based solvents. More specifically, examples include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, ethylene glycol, propylene glycol, butylene glycol, and terpineol; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. These can be used individually or in combination of two or more types.

[0036] There are no particular restrictions on the content of organic solvents, and they can be appropriately selected depending on the purpose. However, when selecting a sandblasting resin composition that contains a large amount of organic solvents, it should be noted that after application to the substrate and drying, the thickness of the sandblasting resist layer may decrease, leading to a reduction in blast resistance.

[0037] <Method for manufacturing a resin composition for sandblasting> The method for producing the sandblasting resin composition is not particularly limited. For example, the above-mentioned components can be blended in predetermined proportions and then kneaded or mixed using a kneading means such as a three-roll mill, ball mill, bead mill, or sand mill, or a stirring means such as a super mixer or planetary mixer. Furthermore, pre-kneading or pre-mixing may be performed before the aforementioned kneading or mixing, if necessary.

[0038] (Surface processing method) The surface processing method according to this embodiment comprises a sandblasting resist layer formation step, a sandblasting treatment step, and a sandblasting resist layer removal step, and further includes other steps as necessary.

[0039] <Sandblasting resist layer formation process> The sandblasting resist layer formation process is a process of forming a sandblasting resist layer on a workpiece using the sandblasting resin composition described above. Specifically, it is a process of applying the sandblasting resin composition to the workpiece and drying or curing it.

[0040] The substrate to be processed is not particularly limited and can be appropriately selected according to the purpose. Examples include glass, stone, ceramics, porcelain, silicone (silicone wafers), quartz, sapphire, metals, metal oxides, plastics, and wood. In the surface processing method of the embodiment, it can also be performed on aluminum, which is a relatively soft metal. There are no particular restrictions on the size or thickness of the substrate to be processed; they can be selected as appropriate depending on the purpose.

[0041] There are no particular restrictions on the coating method applied to the substrate to be processed, and it can be appropriately selected according to the purpose. Examples include doctor blade coating, Meyer bar coating, roll coating, screen coating, spinner coating, inkjet coating, spray coating, dip coating, gravure coating, curtain coating, and die coating.

[0042] The thickness of the resin composition for sandblasting is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of blast resistance, 10 μm to 150 μm is preferred, and 30 μm to 120 μm is more preferred.

[0043] There are no particular restrictions on the drying or curing method, and it can be appropriately selected depending on the purpose. Examples include drying by heat and curing by UV light.

[0044] Heat drying is a method in which a sandblasting resin composition is applied to the substrate to be processed, and then heat is applied to dry it. The drying temperature of the resin composition for sandblasting is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably around 55°C to 130°C. The drying time for the sandblasting resin composition is not particularly limited and can be appropriately selected depending on the purpose, but 30 seconds to 30 minutes is preferred.

[0045] UV curing is a method in which a sandblasting resin composition is applied to the substrate to be processed, and then cured by irradiating it with UV light. There are no particular restrictions on the amount and duration of UV irradiation during UV curing; they can be selected appropriately according to the purpose.

[0046] The sandblasting resist layer may also be formed by applying a dry film. The dry film is obtained by coating a support film with the aforementioned sandblasting resin composition and drying it.

[0047] <Sandblasting process> The sandblasting process is a process of performing sandblasting on a workpiece that has a sandblasting resist layer. Specifically, it is a process of cutting the surface of the workpiece by spraying an abrasive onto the workpiece and the sandblasting resist layer.

[0048] Abrasives (blasting materials) that are known can be used, such as inorganic compounds like silica and glass; metallic compounds like steel, stainless steel, zinc, and copper; ceramics like garnet, zirconia, silicon carbide, alumina, and boron carbide; and particles mainly composed of dry ice.

[0049] There are no particular restrictions on the particle size (volume-average flow diameter) of the abrasive, and it can be appropriately selected depending on the purpose, but it is preferably around 2 μm to 100 μm.

[0050] There are no particular restrictions on the pressure at which the abrasive is sprayed, and it can be selected appropriately depending on the purpose, but 1 kg / cm² is recommended. 2 ~5kg / cm 2 A certain degree is desirable.

[0051] Even when spraying abrasives, mixing them with compressed air from a compressor and spraying them, The process may also be carried out by introducing the workpiece into the sandblaster.

[0052] <Sandblasting resist layer removal process> The sandblasting resist layer removal process is the process of removing the sandblasting resist layer after sandblasting. Specifically, it is a process of peeling and removing the sandblasting resist layer from the workpiece by immersing the workpiece in an organic solvent or by performing tape peeling on the sandblasted layer on the workpiece.

[0053] Examples of organic solvents used to remove the sandblasting resist layer include γ-butyrolactone, glycol ester solvents, and glycol ether solvents. These may be used individually or in combination of two or more. Examples of glycol ester solvents include ethylene glycol monoethyl ether acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, and ethyl carbitol acetate. Examples of glycol ether solvents include methyl carbitol, ethyl carbitol, and ethylene glycol mono-t-butyl ether. Among these, γ-butyllactone is preferred. The immersion temperature of the organic solvent should preferably be around room temperature. There are no particular restrictions on the immersion time in the organic solvent, and it can be selected as appropriate depending on the purpose, but 30 seconds to 30 minutes is preferable.

[0054] Removal by tape peeling is performed by applying tape to the sandblasting resist layer and then peeling off the tape to remove the sandblasted layer. You can use commercially available adhesive tape.

[0055] <Other processes> Other processes are not particularly restricted and can be selected as appropriate depending on the purpose, for example, a cleaning process for the workpiece. [Examples]

[0056] Next, we will describe the tests conducted by the inventors, but the present invention is not limited to these.

[0057] (Examples 1-4, Comparative Examples 1-4) <Preparation of resin composition for sandblasting> The materials were blended in the proportions shown in Table 1, pre-mixed in a stirrer, and then kneaded in a three-roll mill to prepare a resin composition for sandblasting. The values ​​in the table are calculated on a pure content basis. The units in the table are parts by mass.

[0058] [Table 1]

[0059] The details of each component in Table 1 are as follows: • Compounds containing carboxyl and amide groups within the molecule (MoldWiz INT-120IMC, manufactured by AXEL PLASTICS) • Phenoxy resin 1 (PKH-A, Huntsman, softening point: 81°C, molecular weight (Mw): 25,000) • Phenoxy resin 2 (PKH-C, Huntsman, softening point: 89°C, molecular weight (Mw): 43,000) • Phenoxy resin 3 (PKF-E, Huntsman, softening point: 98°C, molecular weight (Mw): 60,000) • Urethane acrylate (Evecryl 270, manufactured by Sartmar) • Silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) • Epoxy acrylate (SP-4010, manufactured by Resonac Co., Ltd.) • Acrylic monomer (Arronix M-5700, manufactured by Toagosei Co., Ltd.) • Asphalt pitch (blown asphalt type, penetration: 6-10, softening point: 110℃, manufactured by Kuju Electric Co., Ltd.) • Thermoplastic elastomer (Asaprene-T-411, manufactured by Asahi Kasei Chemicals Corporation) • Photopolymerization initiator (Omunirad 1173, manufactured by IGM Resins BV) • Pigment (Firstgen Blue 5380, manufactured by DIC Corporation) • Carbon black (MA-100, manufactured by Mitsubishi Chemical Corporation) • Silicone-based mold release agent (KF-96-500cs, manufactured by Shin-Etsu Chemical Co., Ltd.) • Shaxifier (Aerosil #200 fine silica powder, manufactured by Nippon Aerosil Co., Ltd.) • Carbitol acetate (diethylene glycol monoethyl ether acetate, manufactured by Shinko Organic Chemical Industry Co., Ltd.) • Ipsol 150 (aromatic hydrocarbon (10 carbon atoms) mixed solvent, manufactured by Idemitsu Kosan Co., Ltd.)

[0060] The sandblasting resist layer formed from the obtained sandblasting resin composition was evaluated for blast resistance, organic solvent removal, and tape peel removal as described below. The evaluation results are shown in Table 2.

[0061] <Fabrication of test boards> A mirror-finished aluminum material (width: 8mm x length: 50mm x thickness: 5mm) was used as the substrate. After cleaning the surface of the substrate with alcohol, alphabet letters (character size: 3mm x 20mm) were printed using each sandblasting resin composition on a 180-mesh, 20μm polyester plate. After printing, the substrates printed with the sandblasting resin compositions of Examples 1-3 and Comparative Examples 1-3 were dried in a drying oven at 150°C for 30 minutes. For substrates printed with the sandblasting resin compositions of Example 4 and Comparative Example 4, a high-pressure mercury lamp was used to test them at 1,000 mJ / cm². 2 It was UV cured under these conditions.

[0062] <Blast resistance> The fabricated test substrates were sandblasted using ceramic beads with a maximum diameter of 65 μm at a pressure of 3 bar until the surface roughness (Ra) reached 0.8 μm to 1.0 μm. The peeling of the letters from the sandblast resist layer after sandblasting was visually observed and evaluated based on the following evaluation criteria. -Evaluation Criteria- ◎: No peeling of lettering. ○: Peeling of lettering is 1% to 5% △: Peeling of lettering is 6% to 49% ×: More than 50% of the lettering has peeled off.

[0063] <Removal of organic solvents> The fabricated test substrates were immersed in an ultrasonic cleaner containing γ-butyllactone, and ultrasonic waves were applied to remove the sandblasting resin. The time taken until the letters were removed and the aluminum surface was exposed was measured, and the substrates were evaluated based on the following evaluation criteria. -Evaluation Criteria- ◎: Within 30 seconds 〇: Between 31 and 60 seconds △: 61 seconds to 120 seconds ×: More than 121 seconds

[0064] <Tape peel removal> After applying adhesive tape (Scotch 313, manufactured by 3M Japan Ltd.) to the fabricated test circuit board, it was peeled off. After peeling off the adhesive tape, the presence or absence of remaining residue (how much of the characters remained) was observed and evaluated based on the following evaluation criteria. -Evaluation Criteria- ◎: No remaining lettering peeling off. ○: Only a part of the letter remains (only fragments of the letter remain) △: Most of the characters remain (the shapes of the characters are recognizable). ×: All characters remain

[0065] [Table 2]

[0066] The sandblasting resist layers formed using the sandblasting resin compositions of Examples 1 to 4 were found to have good blast resistance and to be able to withstand organic solvent removal and tape peel removal. In contrast, Comparative Examples 1 and 2, which do not contain compounds having carboxyl and amide groups in their molecules, received a "fail" rating for tape peel removal. Comparative Example 1 contains a silicone-based release agent used in a similar manner to compounds having carboxyl and amide groups in their molecules, but also received a "fail" rating for tape peel removal. Therefore, it became clear that including compounds having carboxyl and amide groups in their molecules in sandblasting resin compositions is necessary to improve tape peel removal. Furthermore, Comparative Example 3, which did not contain either phenoxy resin or urethane acrylate, received a "×" rating for blast resistance. Therefore, it became clear that the inclusion of either phenoxy resin or urethane acrylate in the sandblasting resin composition is necessary to improve blast resistance. Furthermore, Comparative Example 4, which contained neither phenoxy resin nor urethane acrylate, but instead contained epoxy acrylate, received a "×" rating for organic solvent removal and tape peel removal. Therefore, it became clear that the inclusion of phenoxy resin or urethane acrylate in the sandblasting resin composition is necessary to improve organic solvent removal and tape peel removal.

[0067] Furthermore, when comparing Examples 1-3, which contain phenoxy resin, with Example 4, which contains urethane acrylate, the evaluation results for organic solvent removal and tape peel removal were "◎" or "〇" for Examples 1-3, while Example 4 was "△". Therefore, using phenoxy resin instead of urethane acrylate can achieve better organic solvent removal and tape peel removal.

[0068] Furthermore, comparing Example 1, where the molecular weight (Mw) of the phenoxy resin was 25,000, with Example 2, where the molecular weight was 43,000, the evaluation of blast resistance was "○" for Example 1, while it was "◎" for Example 2. Therefore, a molecular weight of 43,000 for the phenoxy resin can provide better blast resistance than a molecular weight of 25,000. Furthermore, comparing Example 2, where the molecular weight (Mw) of the phenoxy resin was 43,000, with Example 3, where the molecular weight (Mw) was 60,000, the evaluation of organic solvent removal and tape peel removal was "◎" for Example 2, while it was "〇" for Example 3. Therefore, a molecular weight of 43,000 for the phenoxy resin is better than 60,000 for organic solvent removal and tape peel removal.

[0069] Although embodiments for carrying out the present invention have been specifically described above, the present invention is not limited thereto and can be modified in various ways without departing from its essence.

Claims

1. A resin composition for sandblasting, characterized by containing a compound having a carboxyl group and an amide group in its molecule, and at least one selected from phenoxy resin and urethane (meth)acrylate.

2. The sandblasting resin composition according to claim 1, wherein the content of the compound having a carboxyl group and an amide group in the molecule is 1.5% by mass to 5.0% by mass.

3. The sandblasting resin composition according to claim 1 or 2, further containing a silane coupling agent.

4. A surface processing method characterized by forming a sandblasting resist layer on a workpiece using the sandblasting resin composition described in claim 1 or 2, performing sandblasting, and removing the sandblasting resist layer after sandblasting.

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